Abstract: A device for clamping flexible printing plates onto the plate cylinder of rotary printing presses, wherein the plate cylinder has a concentric groove formed in its surface, the groove walls extending at an acute angle into the surface of the plate cylinder to define a pair of hook-like edges at the groove opening for receiving the correspondingly hook-like bent ends of the printing plate. A spindle is pivotably disposed in the groove having an axis concentric with the groove. At least one flange spring is supported on a first side of the spindle which faces a first hook-like wall edge. A clamping element is formed at one the end of the spring for engaging the front end of the printing plate against one of the hook-like groove edges. A bar disposed on the opposite side of the spindle axis and mounted to the spindle, the bar extending into the plate cylinder surface for receiving the hook-like bent rear end of the printing plate.